Typology of representative building designs within townships for energy efficiency in the City of Cape Town

Thesis (MPhil)--Stellenbosch University, 2016.ENGLISH SUMMARY : African urbanisation currently embodies spaces that represent every scale of urban development. In the case of the City of Cape Town Municipality (CCT) in South Africa, the built environment is responsible for almost 40% of the total primary energy use. However, the preliminary investigation uncovered that there is currently limited understanding of the energy profiles of the various types of low cost buildings found within townships in South Africa, and that successful implementation of plans for sustainable energy provision within this sector is uncommon. In order to understand CCT’s inclusive urban metabolism, the study sets out to fill this gap in knowledge and data regarding the current urban energy systems in the low cost building sector. The primary research aim of the study was to build a typology of low cost buildings, with regards to their energy profiles. As it is necessary to address the energy challenges holistically, the complexity and interconnectedness of socio-economic, environmental and energy systems were considered. In order to achieve this, the following methods were employed: literature review; typology building; energy and thermal comfort modelling; and semi-structured interviews. The literature review followed themes of urbanisation; urban metabolism; sustainability in the built environment; low-cost buildings in Africa; and the energy landscape in South Africa, especially with regards to township architecture. To develop the building energy typology, 46 suburbs were identified as townships in the City of Cape Town, of which two representative ones were studied, namely Gugulethu and Manenberg. The buildings within these townships were classified into nine representative types: rowhouses; maisonettes; cottages; courts; government reconstruction and development programme (RDP) houses; single storey migrant labour hostels; two storey migrant labour hostels, and buildings known colloquially as ‘2-storeys’. Based on the building properties for each of the nine representative building types, energy consumption was modelled using DesignBuilder software. According to the four energy use consumption sources (heating; cooling; lighting and domestic hot water), the buildings were grouped relatively into three levels of consumption typologies: low, medium and high. Cottages and the two-storey migrant labour hostels formed the low consumption typology; maisonettes, single storey migrant labour hostels and ’2-storeys’ formed the medium consumption typology; and rowhouses, courts and RDP houses formed the high consumption typology. Results of the energy profile simulations revealed that the main reasons for high energy consumption within township buildings was due to the often poor orientation of buildings on site; high occupancy rates; uninsulated walls and roofs; lack of ceilings; air leakage due to a lack of (properly) fitted window and door frames; the use of kettles as a primary source of water heating; and inefficient incandescent lighting. Thermal gains graphs, also generated from DesignBuilder, revealed that most of the building types were thermally inefficient, i.e. they are hot in summer, and cold in winter due to lack of airtightness; overheating from a lack of shading elements; poor insulating capacity of structural components; and/or high occupancy loads. To enable future energy efficient design interventions in townships, the findings suggest that public and private entities need to become more transparent regarding the types of data available, and develop the existing data in order to encourage research-backed policies and projects which could lead to an alternative model of (township) construction. Retrofitting projects should incorporate ceilings in their design; provide wall insulation; plaster walls; use lightweight materials where possible; allow for customisation and expansion from original design; offer appropriate roof materials and shading elements; conduct airtightness tests; consider cultural positions on built structure; offer solar water heaters and rooftop PV; and replace incandescent light bulbs with energy efficient lighting. New buildings should also consider the orientation of the building on site. Future work involves alleviating data scarcity challenges in this sector by making new data publicly available; quantifying the considerable amount of informal energy use within townships; and finding a means of consolidating different forms of energy profiling into a singularly measurable output. In order to meet the aim of understanding the city’s inclusive urban metabolism, it is vital that this data is combined with data on formal and existing energy flows, and modelled alongside the other relevant resource flows within the city.AFRIKAANSE OPSOMMING : Soos verstedeliking in Afrika tans daar uitsien, is daar ruimtes wat stedelike ontwikkeling op elke moontlike skaal verteenwoordig. In die geval van die Stad Kaapstad Munisipaliteit (SKM) in Suid-Afrika verteenwoordig die geboude omgewing ongeveer 40% van die totale primêre energieverbruik. Die voorlopige ondersoek het egter aangedui dat daar onvoldoende insig in die energieprofiele van die onderskeie soorte laekostegeboue in die townships van Suid-Afrika is, en dat planne vir volhoubare energievoorsiening in hierdie sektor selde suksesvol geïmplementeer word. Ten einde ’n duideliker begrip van die SKM se inklusiewe stedelike metabolisme te kan bekom, pak hierdie studie die kennis- en datagaping ten opsigte van die bestaande stedelike energiestelsels van die laekostebousektor aan. Die primêre navorsingsoogmerk met die studie is om ’n tipologie van laekostegeboue met die oog op hulle energieprofiele saam te stel. Omdat hierdie energieuitdagings holisties aangepak moet word, is die kompleksiteit en die onderlinge verbondenheid van sosio-ekonomiese, omgewings- en energiestelsels in ag geneem. Die metodes wat gebruik word om hierdie oogmerk te bereik, behels onder meer ’n literatuuroorsig; tipologiesamestelling; energie- en termiesegerief-modellering; en semi-gestruktureerde onderhoude. Temas wat in die literatuuroorsig ondersoek is, sluit in verstedeliking; stedelike metabolisme; volhoubaarheid in die geboude omgewing; laekostegeboue in Afrika; asook die energielandskap in Suid-Afrika, veral wat die township-argitektuur betref. Vir die samestelling van die gebou-energietipologie is 46 woongebiede as townships van die Stad Kaapstad geïdentifiseer, en twee verteenwoordigende gebiede, te wete Gugulethu en Manenberg, is in die studie gebruik. Die geboue in hierdie townships is in nege verteenwoordigende tipes verdeel, te wete: skakelhuise; skakelwoonstelle; kothuise; howe; die staat se heropbou-en-ontwikkelingsprogramhuise (HOP-huise); enkelverdiepinghostelle vir trekarbeiders; dubbelverdiepinghostelle vir trekarbeiders; en geboue wat in die volksmond ’2-verdiepings’ genoem word. Energieverbruik is met behulp van DesignBuilder-sagteware gemodelleer na aanleiding van die geboukenmerke van elk van die nege verteenwoordigende geboutipes. Met die vier energieverbruiksbronne (verhitting; verkoeling; verligting en huishoudelike warm water) in ag genome, is die geboue tipologies volgens drie verbruiksvlakke geklassifiseer: laag, medium en hoog. Kothuise en tweeverdiepinghostelle vir trekarbeiders verteenwoordig die laeverbruiktipologie; skakelwoonstelle, enkelverdiepinghostelle vir trekarbeider en ’2-verdiepings’ vorm die mediumverbruikstipologie; en skakelhuise, howe; en HOP-huise maak die hoëverbruiktipologie uit. Volgens die resultate van die energieprofielnabootsings is die hoofredes vir energieverbruik in township-geboue grootliks te wyte aan die swak oriëntasie van die geboue op die perseel; hoë okkupasiekoerse; ongeïsoleerde mure en dakke; gebrek aan plafonne; ontsnapping van lug vanweë ’n gebrek aan (behoorlik) geïnstalleerde venster- en deurrame; die gebruik van ketels as primêre waterverhittingsbron; en ondoeltreffende gloeilampverligting. Termiesetoename-grafieke wat ook met DesignBuilder geskep is, dui daarop dat die meeste geboutipes termies ontoereikend is, dit beteken die geboue is warm in die somer en koud in die winter vanweë onvoldoende lugdigtheid; oorverhitting by gebrek aan beskaduwingselemente; swak isoleerkapasiteit van strukturele komponente; en/of hoë okkupasieladings. Die bevindings dui op bepaalde voorvereistes betreffende toekomstige ontwerpintervensies om informele nedersettings energiedoeltreffend te maak, naamlik samewerking tussen openbare en privaat entiteite en die ontwikkeling van die bestaande data met die oog op navorsingsgesteunde beleide en projekte om ’n alternatiewe model van township-ontwikkeling aan te moedig. Herbouprojekte behoort plafonne in die ontwerp in te sluit; muurisolering te voorsien; muurpleistering te doen; liggewigmateriaal te gebruik waar moontlik; die oorspronklike ontwerp aan te pas en uit te brei; gepaste dakmateriaal en beskaduwingselemente aan te bied; lugdigtheidstoetse uit te voer; kulturele posisies oor geboude strukture te oorweeg; sonwaterverhitters en fotovoltaïese dakstrukture aan te bied; en gloeilampe met energiedoeltreffende verligting te vervang. By nuwe geboue moet die oriëntasie van die gebou op die perseel in ag geneem word. Werk vir die toekoms behels om die uitdagings van die dataskaarste in hierdie sektor aan te pak aan die hand van nuwe data wat van owerheidsweë bekom word; die aansienlike hoeveelheid informele energieverbruik in townships te kwantifiseer; en te bepaal hoe verskillende vorme van energieprofilering in ’n unieke meetbare uitset gekombineer kan word. In orde om die stad se inklusiewe metabolisme te verstaan is dit krities dat hierdie data saamgevoeg word met bestaande en formele data op energiestrome, en langsaan ander relevante hulpbronbewegings in die stad verstaan word